1. Field of the Invention
The present invention relates to a technique for providing fast incremental archive of permanent storage using minimal archive storage space.
2. Background Information and Description of the Related Art
Many computer systems employ a conventional archiving scheme to back up one or more disks. This archiving scheme writes a copy of an entire file to magnetic tape each time a user modifies and archives that file. If subsequent modifications are made to the file and the user again desires to archive it, the archiving scheme appends the entire file to the previously archived file on tape.
This archiving scheme presents disadvantages and limitations. First, even if the user makes the smallest modification to a file, the archiving scheme writes the entire file to tape when the user archives it. Therefore, this archiving scheme requires substantial amounts of time to archive large files. Second, because this archiving scheme appends each archived file to the end of the previously archived file, additional amounts of tape are continuously required.
Accordingly, great demand exists for an archiving system that is much faster than conventional archiving schemes and requires no additional tape. Such an archiving system should not completely rewrite a file each time a modification is made, but rather should only rewrite or archive the modified sections of that file.